Insight into the stabilization mechanism of emulsions stabilized by Maillard conjugates: Protein hydrolysates-dextrin with different degree of polymerization

The physical and oxidation stability of emulsions stabilized by conjugates prepared by Maillard reaction between whey protein hydrolysates (WPH) and linear dextrin (LD) with different degree of polymerization (DP) were investigated. In accordance with the gradient ethanol precipitation, LD1 (DP = 23.78), LD2 (DP = 47.62) and LD3 (DP = 64.96) were prepared. WPH-LD conjugates were obtained by Maillard reaction in dry-heating condition and the degree of glycation (DG) of conjugates increased with the increasing content of LD. Structural analysis (fluorescence spectra and circular dichroism) revealed that the secondary structure of WPH changed after glycation and the conjugates had less alpha-helix content than unmodified WPH. Meanwhile, the greater DPPH radical scavenging ability and iron chelating activity of conjugates were demonstrated compared with unmodified WPH. Conjugates containing LD with low and middle DP could form Pickering emulsions due to the aggregation of LD with short chains. The superior storage stability, oxidative stability and physical stability against environment stress of emulsions stabilized by conjugates, enhanced with increasing DP of LD in conjugates, were attributed to the combined action of stabilization of particle emulsifiers and greater steric hindrance (occupied the dominant position) provided by conjugates. Maillard reaction between LD and WPH was efficient to produce conjugates with high potential use as emulsifying agents to stabilize emulsions with excellent physical and oxidative stability.